Problems with the password for dc_sources.zip

Our company has bought licenses for the PKI, PDF and DC packages. Now I have the "dc_sources.zip" I can open it with winzip and I can view which files are inside. But when I try to unzip the "dc_sources.zip", it asks me for a password. I have tried letting it in blank, putting the ticket number of the DC, and also I have tried to put the DC license code. But it looks like no one of these passwords is the needed one. How can I know which is the one I must input?

1) If you have a license, please link the license ticket to your user account before we continue. The ticket itself and the procedure of its use are specified in the registration e-mail that was sent to you upon license purchase. If you don't have the license ticket, please contact the person from which you have obtained the license key (the one in your source code) for a license ticket.